The retail giant ends its 'business relationship' with Mercury Public Affairs, whose senior associate was found to have posed as a reporter at an event staged by Wal-Mart critics.

Retail giantWal-Martsaid that it has parted ways with a public relations firm whose employee was found to have posed as a reporter at an event staged byWal-Martcritics.

Wal-Martspokesman Steven Restivo said in a statement Friday that his company and Mercury Public Affairs had mutually decided to end their "business relationship." Mercury had received $60,000 to lobby officials at Los Angeles City Hall over a proposed Wal-Mart grocery in Chinatown, according to city records.

"We take this matter seriously and have taken the appropriate steps to ensure this type of activity is not repeated," Restivo said.

The announcement came one week after the employee group Warehouse Workers United revealed that Mercury senior associate Stephanie Harnett had shown up at one of its news conferences and posed as a USC student journalist. During that event, she recorded an interview with a worker, according to the group.

Harnett left the firm last week. Mercury said it was taking "full responsibility" for what happened but had not directed or instructed Harnett to pose as a reporter.

"She was a junior member of our team and showed very poor judgment and we dismissed her from our firm as these actions run contrary to our firm's culture and values," said Mercury managing director Becky Warren in an email. Warren would not say whether her firm had been working on other Wal-Mart store sites.

Warehouse Workers United has accused Wal-Mart of failing to ensure that contractors at its warehouses in the Inland Empire are paying their employees minimum wage and providing them with regular breaks and air conditioning. The group had been calling for Wal-Mart to jettison Mercury over the Harnett incident.

"We expect that Wal-Mart will extend its commitment to integrity to all contractors, including those that run its warehouses," said Elizabeth Brennan, spokeswoman for the warehouse employee group. "We hope Wal-Mart will operate with consistency with all of its vendors, not just those that are embroiled in scandal."